1. Field of the Invention
The present invention relates to an amplifier to convert a pair of unbalanced currents into a balanced pair of voltages, in particular, the invention relates to an amplifier implemented with an optical receiver.
2. Related Background Arts
An optical receiver generally includes a light-receiving device such as photodiode (hereafter denoted as PD), and an amplifier to convert a photocurrent generated by the PD into a voltage signal. The amplifier generally has the configuration of, what is called, the trans-impedance amplifier (hereafter denoted as TIA) and some controllers to control the voltage signal, for instance, to adjust the output offset contained in the voltage signals when the PD and the amplifier have the differential arrangement.
The PD, when it senses an optical signal with high frequency components and large power, is necessary to be biased by an enough bias voltage. While, a continuous requests for electronic apparatus has been presented to reduce the power consumption and lower the supply voltage thereof, which contradicts the request to supply enough bias voltage to the PD. The present invention provides one of solutions to this inconsistent request.